ICU · Oncology

Tumour lysis syndrome

Also known as Tumour lysis syndrome (TLS) · Hyperuricaemia · Rasburicase · Acute tumour lysis syndrome (ATLS) · Cairo-Bishop classification · Urate nephropathy · Tumor lysis syndrome

Tumour lysis syndrome (TLS) is a metabolic oncological emergency from rapid malignant cell lysis releasing intracellular contents: HYPERKALAEMIA (intracellular K+ dumped — most dangerous, causes fatal arrhythmia), HYPERPHOSPHATAEMIA (phosphate-rich malignant cells release their intracellular phosphate load), HYPOCALCAEMIA (secondary — Ca2+ precipitates with phosphate as calcium-phosphate crystals), and HYPERURICAEMIA (nucleic acid breakdown → purines → xanthine → uric acid via xanthine oxidase). Uric acid and calcium-phosphate precipitate in renal tubules → acute kidney injury (AKI), which then reduces K+ and phosphate excretion → a self-amplifying vicious cycle. Onset typically within days of starting chemotherapy/radiotherapy/corticosteroids/targeted therapy for high-turnover tumours (ALL, Burkitt lymphoma, lymphoblastic lymphoma, high-grade NHL, AML); spontaneous TLS can precede therapy in bulky disease. Cairo-Bishop definition: laboratory TLS (≥2 abnormal values — urate ≥8 mg/dL/476 µmol/L, K+ ≥6.0 mmol/L, phosphate ≥4.5 mg/dL adult/≥6.5 child, Ca2+ ≤7.0 mg/dL/1.75 mmol/L, or 25% change within 3 days before to 7 days after therapy) vs clinical TLS (LTLS PLUS AKI, arrhythmia/sudden death, or seizure). Prevention is the cornerstone: aggressive IV hydration 2500-3000 mL/m2/day (goal urine output ≥2 mL/kg/h) + rasburicase 0.20 mg/kg/day IV for HIGH risk (recombinant urate oxidase — converts EXISTING uric acid → soluble allantoin; CONTRAINDICATED in G6PD deficiency) or allopurinol 300 mg/day for INTERMEDIATE risk (xanthine oxidase inhibitor — prevents NEW uric acid only). Treatment: aggressive hydration, rasburicase, treat hyperkalaemia per protocol (calcium gluconate → insulin-dextrose → salbutamol → binders → RRT), do NOT routinely treat asymptomatic hypocalcaemia, RRT for refractory electrolyte disturbance or AKI. Do NOT alkalinise urine (worsens calcium-phosphate precipitation).